Yale Papyrus Collection

grid

Pages from Elizabeth Peabody's Universal History: Arranged to Illustrate Bem's Charts of Chronology. New York: Pub. for the author by Sheldon and Co, 1859.
A system for charting historical events on a grid (representing historical periods, arranged chronologically); squares, divided into 9 parts each, to represent distinct categories of historical events; and colors, to show different "Nations".